“(They’re) about a billion times beneath levels that would be health threatening,” a diplomat with access to radiation tracking by the U.N.‘s Comprehensive Test Ban Treaty Organization told the Associated Press.

The diplomat in Vienna said the initial reading came from an unnamed measuring station operated by the CTBTO, apparently in Sacramento.

Experts agree that any fallout wafting 5,500 miles across the Pacific to California will be too diluted to pose a health risk.

“It would be less than one microsievert,” Dr. Keisuke Iwamoto, a radiation biologist at UCLA, told the Daily News. “To give you some perspective, a chest x-ray might be 100 microsieverts.”

Still, some jittery residents are hoarding anti-radiation pills and fretting over the invisible threat as weather systems beat a path between the crippled Fukushima Daiichi plant and California.